System of air and wire radio communication and alarm



July .14, 1942. B. E. covER, sR

SYSTEM 0F AIR AND WIRE RADIO COMMUNICATION AND. ALARM Filed July 14, 1941 2 Shgeis-Sheet 1 ATTORNEY.

July 14, 1942.

B. E. COVER, SR

SYSTEM OF AIR AND WIRE RADIO COMMUNICATION AND ALARM` 2 Sheer,:s--.'Sheei 2\ Filed July 14, 1941 INVENTOR.

ATTORNEY.

Patented July 14, 1942 SYSTEM OF AIR AND WIRE RADIO COMMUNICATION AND ALARM Berkey E. Cover, Sr., Chicago, Ill., assigno'r, by

mcsneassignments, to Electra-Voice Corporation, Wilmington, Del., a corporation of Dela- Ware 'Applicata-en July 14, 1941, serial No. 402,313

6 Claims.

My present invention has to do with improvements in a system for transmitting signals, alarms, inter-communicating messages between a central station and a plurality of subsidiary local stations. Patent No. 2,129,345 was issued to me September 6, 193,8, for certain improvements in i such a system which was peculiarly suitable for handling the iire and police business of a metropolitan or other politicalarea and the present invention constitutes a further extension and deject to wide variations. Generally speaking transmission can be eiected both day and night and with a high degree of certainty and with simple and low power apparatus when the ldistance of transmission is but a few miles, and such transmission has the great additional advantage of causing practically no interference with other radio transmission and reception. The arrangement of a central station with subsidiary stations located to cover separate portions of the general area lends itself to the employment of certain simple, low power, non-interfering radio communicating apparatus not onlyfor political areas but much less extensive properties such as factories and factory parkings and public reservations of various kinds and extents.

` Among my specic objects has been to .provide instrumentalties to cause and control radio transmission and reception at one or more of the subsidiary stations from the central station and also to permit radio transmission and reception from each of the subsidiary stations. I have also had as a further object, the association with the equipment required for such radio service, of an electric eye whichwill apprise those in control of and operating the system, of an unauthorized entry of the premises, should such an entry occur.

The system Vset forth in the heretofore mentioned patent involves the employment, among other elements`,vof a central station, provided with standard central station equipment,` and a plurality of subsidiary stations in the form of street boxes with a metallic circuit between each of the street boxe'sand the central station. Each street box, as is not unusual, is provided with an upper and lower compartment.` The upper compartment is closed. by a door without a lock so that the door may be opened and the apartment entered at will by any individual of the public who may have occasion to do so.' When the door to the upper compartment is opened, the circuit carrying normal D. C. power from the central station is luy-passed around a relay for certain purposes, but, because of the proper disposal of suitable inductance and capacity, alternating and modulated currents may still pass between the street box and central station when the direct current is discontinued. Among otherV apparatus installed in the upper compartment is a microphone and a loud speaker suitable for and capable of receiving and reproducing articulate sound. The lower compartment of the street box is closed by a door provided with a lock, keys for the opening of which are carried by policemen and liremen or others charged with, duties having to do with the operation and use oi the system. In the lower locked compartment is installed a monophone, preferably of the cradle variety, by means of which messages may be sent and received with a considerably greater degree of local privacy.

All of the above is either standard practice or set forth in the heretofore mentioned patent.

In addition to and in combination with the above indicated elements of standard and patented equipment, I have attained the herein mentioned, objects, by means of the elements and organization thereof illustrated in the accompanying drawings in which- Fig. 1 is a diagrammatic illustration of elements and wiring involved in sending and receiving from antenna at area-box from central station.

Fig.- 2 is a diagrammatic illustration of elements and wiring involved in .sending and receiving from an area-box. A

Fig. 3 is a diagrammatic illustration of elements and wiring involved in sending and receiving by means of mon'ophone from locked compartment of area-box.

Fig. 4 is a diagrammatic illustration of the association of electric eyes with the area-boxes of a system.

In the project of covering an area from the point of view of radio transmission and reception by means of a central station connected with a series of subsidiary stations so` located `as to assure dependable communication with equipment ci a suitable character operating with relatively little power, the problem involves transmitting and receiving at the central station from an antenna at an area-box. The second main problem is to transmit and receive at the areabox. While the last above named problem is subsidiary, in a way, to the main problem of equipping the system shown in Patent No. 2,129,384 with radio communication, it may, nevertheless, be of great practical importance as the solution thereof provides communication between the central station and an area-box when, and if, the metallic line circuit be destroyed or otherwise interrupted.

'Ihe third problem involves the provision of simple and effective mechanism permitting radio transmission and reception by means of the monophone installed in the lower locked compartment of the street or area-box. The solution of this latter problem provides more locally condential communication with the central station independently of, as well as with, the metallic line wire connecting these stations.

As will hereafter be seen, the arrangement I have provided for connecting at will the radio transmitter and radio receiver with the antenna and the line is substantially the same in the solution of the three separate problems except in the way in which the actions are initiated.

In addition to the instrumentalities described in Patent No. 2,129,384, I have installed in the subsidiary street or area-box a radio transmitter,

a radio receiver, an antenna, two double relays and a polarized relay. It will be seen by reference to said patent that there is already installed in said subsidiary street or area-box, a local six volt battery, a relay and a switch for by-passing said relay when the door to the upper compartment of said box is open, a microphone, a loudspeaker and, of course, suitable connections for the metallic circuit or line. It will be borne in mind that the transmission of the high frequency current employed in radio communication between the central station and the area-box can be accomplished over a line connecting these points through inductive and capacity linkage and is wholly independent of the closed circuit which is required for sending battery current between these points.

In the three cases mentioned above, to wit, sending and receiving from the central station with the upper door closed, sending and receiving from the street or area-box with the upper door open and sending and receiving with the monophone as respectively shown in Figs. 1, 2, and 3, the same variety of instrumentality is employed in connecting the antenna with either the transmitting or receiving set and for connecting the set with the local loud speaker in the first two instances, and with an inductance of the monophone, in the third instance. These instrumentalities comprise besides the antenna designated by the reference numeral 9, a radio transmitter 1, a radio receiver Il, double relays 8 and I2 for connecting the radio units with the antenna and the line respectively, and a polarized relay 4.

The lower blade Bb of relay 8 connects the transmitter through capacity I0 with the loud speaker, Likewise the upper blade I2a of relay I2 connects the radio receiver Il with the antenna 9, and the lower blade |219 of this relay connects through capacity I9 with the loud speaker.

In Fig. 3, the lower switch blades 8b and I2b of relays 8 and I2, instead of connecting the radio transmitter and radio receiver respectively with the loud speaker, connects these elements with the central inductance winding T of the monophone.

Referring particularly to Fig. 1: the central operator places energy on switch blade 5a of relay 5 by means of reversing the polarity on the line L running between the central station and the street or area-box through the instrumentality of the polarized relay 4. It will be recollected that the upper'door of the street or area-box is closedy and therefore the by-passing switch 6, controlled by said door, is open, therefore, the switch blade 5a is in its upper position in which position it makes contact at m with a lead running to the radio receiver Il and energizes the lower relay I2.

At the left of Fig. l, is a schematic layout of the wiring of the central oiiice equipment, so designated, in which the top and bottom lines L indicate the line or circuit between the central oice and the street or area-box. I have indcated the positive and negative polarity which is normal to the circuit or line. The polarity is changed by a jack or cam-switch, as may be desired, which results, as shown in Fig. 1, in opening the contacts L3 and L4 and closing the contacts LI and L2, The polarity is then indicated at the center left in diagram 3 of the central station, and, as heretofore described, the polarized relay 4 is operated to close contact in the street or area-box between the lead from the six volt battery B and the lead to the blade 5a of relay 5.

In order to send, or broadcast, the central office operator presses the button of the switch marked send which disconnects the current of reversed polarity from the line and connects the line with the central office loud speaker coil 3l, so designated. The removal of all direct current energy from the line de-energizes relay 5 and permits the blade 5a to fallfinto contact b in which position, as heretofore described, current flows to the radio transmitter 1, and the radio transmitter I is connected by means of energizing relay 8, through blade 8a with the antenna, and the radio transmitter is connected by blade 8b with the loud speaker.

To receive, the central ofce operator releases the button designated send and presses the button to the left designated receive which .connects the reversed line current with the line running to the street or area-box. The energy of this current picks up the blade 5a of relay 5 to make contact at m which, as previously described, transmits energy to the radio receiver II and to relay I2 which connects the radio receiver II through blade I 2a with the antenna, and, through blade |212, with the capacity coupling Ill to the line L which transmits over the line to the receiver at the central station. When the receive button is pressed the reversed line current, as shown by the diagram, is applied to the operators receiver at the central oice. It should also be noted that the polarized relay will not restore when the line current is cut off, but only operates upon a reversal of the line current.

Proceeding now to Fig. 2: this is a schematic diagram of the conditions obtaining when broadcasting and reception are had when the upper door of the street or area-box is open. It will be remembered that/when the door to the upper compartment is open the by-pass 6 of the relay 5 will be continuously closed and the switch blade 5a will be continuously closed at contact b.

To the left of Fig. 2 is shown at I3 wiring of a cam-switch, the forward pull of which operates the connections at the right designatedv send and the rearward movement of which operates the switches shown in the left portion of I3, designated receive T'he wiring is as follows; the positi-ve pole of the six volt local ba-ttery B `is connected with the lower Vcontact I3a of `the send arrangement and the lower contact I 3a of the send arrangement is connected with the lower contact |39 of the receive arrangement. The lower blade |311 of the send arrangement is connected with the line L which runs through the loud speaker, microphone, by-pass B and polarized relay 4 and terminates in the upper blade I3e of the send arrangement. i

The normal negative line` from the central oflice connects with the upper contact `|31 of the lower switchblade 13h. of the receive arrangement which blade, I3h, in turn, is connected with the upper contact |3c of the lower switch blade |312 of the send arrangement. The upper conductor from the central office connects with contact |37' of the receive arrangement. The blade ISIC with which the last mentioned contact normally contacts, is connected with the lower contact I3d of the upper blade I 3e of the send portion of the switch. The upper contact I3f of the upper blade I3e of the send arrangement is grounded or connected with a tap from the negative pole of the six volt local .battery B. After the door has been opened, positive current from the central office will come in through contact |31' and will pass through blade |3lc, to contact I3d and blade I3e, out around the line L in the normal manner and pass back to the central station through the lower blades |3b and |311. of respectively the send and receive arrangements and their upper contacts, respectively |3c and |31'. Contact |3Z of blade I3lc of the receive arrangement is wired to grounded contact ISf ofthe send arrangement.

Normally the contact I3m is in contact with blade |312 of the receive arrangement saidV blade being connected with contact b of blade 5a of relay 5 and contact 5m being wired to, and connected with, radio transmitter I and relay 8. The contact |30 of the blade |311 of the receive arrangement is wired to the radio receiver II and relay I2 whereby the radio re- #i ceiver is connected respectively with the antenna and the loud speaker.

To send or broadcast, the cam-switch I3 is pulled forward which breaks contact between contact |30 and blade I3b` and makes contact between said blade |312 and contact |311., and also blade I3e breaks contact with contact |3d and makes Contact with contact |31. By reference to Fig. 2 it will be seen that the central omce line circuit has been broken and the local six volt battery B has been put on the line with reverse polarity which causes the blade 4a of the polarized relay 4 to contact point 4c which is wired to blade 5a. which, through its contact in released position, places energy on blade |311. and through contact |3m places energy on radio transmitter 'I and relay 8.

To receive, cam I3 is pushed rearwardly which restores the original normal condition of the send blades and contacts, but, through the breaking of! the blade |3h from contact |32" and the making of contact between said blade |311. with contact I3g and the shifting of blade |37c to contact |31 the opening of the circuit of the central oflice circuit is continued and the local per compartment.

battery B is connected with the line circuit in precisely the same polarity' as during the sendfing operation. However, blade |311. has now been transferred from contact |3111. to Contact |30 which is wired to` radio receiver II and relay I2.

Referring now to Fig. 3; the door of the upper compartment of the street or area-box is closed and the policeman, fireman or other authorized person having a key to said box, opens the lower locked door and removes the monophone. It will be `perceived that the monophone can be operated with a much greater degree of local privacy than can be the microphone in the up- For the sake of simplicity I have omitted indicating the means of breaking the upper normal line circuit from the central station which can be done in a number of ways and have restricted myself to showing application of the power of the six volt local battery B, which is all that is employed in this operation with the moncphone, radio transmitter and receiver and relays for sending and receiving. Two buttons are all that need by employed, one to receive and one to send. When the send button M is pressed it makes contact with the positive lead M2 from the battery B and is wired to the primary. and secondary coils P and S of the monophone inductance 21, the send relay 8 and the radio transmitter '1, from which radio transmitter the current is returned to the central inductance T of the monophone.

When the send button M is released and the receive button R. is pressed, positive local battery current is Vplaced on relay I2 and radio receiver II which is likewise connected with the central incluctance of the monophone.

The employment of a system comprising a central station and street or area-boxes in the transmission of messages or alarms by wire has the considerable advantage of great convenience in reaching an area-box for the purpose of transmission and reception. The extension of such a system to radio communication not only has the same advantage as with line communication but has also, in addition, the further considerable technicalA advantage of covering the area with vastly greater certainty by means of more economical equipment than is necessary in the employment of radio communication over longer and more varying and uncertain distances without interference.

I have availed myself of the equipment described in the heretofore mentioned patent, and,

' in this application have associated therewith air and wire radio communication and an electric eye alarm signal. The equipment shown in Fig. 4 is installed in the street or area-box and the apparatus for generating the ray may be located at a desired distance from the area-box and in a situation to be interrupted by a person entering the premises without authorization. The apparatus installed in the box comprises a tube or electric eye Ia which connects through suitable resistances Ib and Ic with a conductor Id independently connected with the power through resistance Ie and If. The conductor Id is connected with an amplier Ig which both generates and ampliiiies a humming note which humming note goes through conductor Ih to relay Ik which operates to place the note carrying circuit across the communicating line L-L between the central station and the area-boxes. When the balance of this circuit is disturbed by a change in resistance of the tube I, the note is produced and imparted to the line. It should be borne in mind that the hum is of such a character that it will not interfere with any of the operations which may be in progress with the street or areaboxes, but, when going, advises everyone having to do with the system, of the existence of the alarm.

Having described my invention what I claiIn as new and desire to obtain by Letters Patent is:

l. A system of short distance radio communication comprising a central station and a plurality of area stations positioned to cover a desired locality, said area stations being at relatively short distances from said central station, a metallic circuit extending between said central station and said area stations, each of said stations provided with antenna and transmitting and receiving radio equipment and means controlled by the polarity and continuity of current passing from said central station and area stations and at said area stations for causing selective transmission and reception from said antenna.

2. A system of radio communication comprising a central station and a plurality of area stations positioned at relatively short distances to cover a desired area, metallic circuits extending between said central station and said area stations, said area stations each being equipped with antenna and sending and receiving radio equipment and means controlled by the polarity and continuity of current passing between said central station and said area stations and at said area stations for causing radio transmission and reception from said antenna and through said metallic circuit between the central station and said area station.

3. A system of radio communication comprising a central station and a plurality of area stations positioned at relatively short distances to cover a desired area, metallic circuits extending between said central station and said area stations, said stations each being equipped with antenna and sending and receiving radio equipment and means controlled by the polarity and continuity of current passing between said central station and said area stations and at said area stations for causing radio transmission and reception from said antenna and through said metallic circuit between the central station and said area station and an electric eye with a balanced circuit and a hum producing and amplifying device with a relay controlled by the balanced circuit of said electric eye for transmitting said hum on the circuits between said stations.

4. A system for the transmission of radio communication and alarm over short distances by air and wire comprising a central station, area stations, wire communication therebetween, antenna upon said stations, sending and receiving equipment provided in said area stations and means operable at said respective stations controlling the polarity and continuity of current flowing thereat for selectively transmitting or receiving from said antenna.

5. A system of radio communication comprising a central station and a plurality of street or area-boxes each connected with said central station by a metallic circuit, said metallic circuit having interposed therein capacity and inductance whereby alternating current may pass therethrough when said metallic circuit is open, radio transmitting and radio receiving sets being mounted in said street or area-boxes and means controlled by current passing between said central Station and said street or area-boxes and the polarity and discontinuity of said current for selectively transmitting or receiving from the antenna of said street or area-boxes and over the circuits extending therefrom.

6. In a system of radio communication comprising a central station and a plurality of street or area-boxes, a metallic circuit connecting said central station with said area-boxes, said areaboXes having an unlocked and -a locked compartment, a radio transmitting and a radio receiving set installed in said street or area-box, an antenna mounted thereon, a microphone and a loud speaker mounted in said unlocked compartment and means including the opening of the door of said unlocked compartment for selectively transmitting or receiving and a monophone disposed in said locked compartment whereby transmission and reception is had from the antenna and over the metallic circuit.

BERKEY E. COVER, SR. 

